1. Field of the Invention
This invention relates generally to chemical vapor detection apparatus and more particularly to a highly sensitive chemical sensor fabricated on a semi-insulating gallium arsenide substrate.
Chemical vapor detectors consisting of bulk or surface acoustic wave devices are generally known and are typically fabricated on quartz. Such devices, however, must be used in a hybrid circuit configuration in order to achieve a desired chemical detecting function. Examples of such detectors/sensors are described in U.S. Pat. No. 5,076,094, issued to Fry et al on Dec. 31, 1991 and entitled "Dual Output Acoustic Wave Sensor For Molecular Identification," and U.S. Pat. No. 4,895,017, issued to Pyke et al in January, 1990 and entitled, "Apparatus and Method for Early Detection and Identification of Dilute Chemical Vapors," both of which are incorporated herein by reference.